max / makenotwork

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1	//! endorsement reads, batched over a post set rather than per post
2
3	use super::{PgPool, Uuid};
4
5	#[derive(sqlx::FromRow)]
6	pub struct EndorsementRow {
7	pub post_id: Uuid,
8	pub endorser_id: Uuid,
9	}
10
11	/// One post's total endorsement count (from an aggregated `GROUP BY`).
12	#[derive(sqlx::FromRow)]
13	pub struct EndorsementCount {
14	pub post_id: Uuid,
15	pub count: i64,
16	}
17
18	/// Batch-fetch endorsements for a set of post IDs.
19	///
20	/// Loads one row per endorsement, fine when the caller needs the endorser ids,
21	/// but the thread view must NOT use this: a hot post with thousands of
22	/// endorsements would stream every row on every (unauthenticated, unthrottled)
23	/// page load. That path uses [`count_endorsements_for_posts`] +
24	/// [`list_user_endorsed_posts`] instead.
25	#[tracing::instrument(skip_all)]
26	pub async fn list_endorsements_for_posts(
27	pool: &PgPool,
28	post_ids: &[Uuid],
29	) -> Result<Vec<EndorsementRow>, sqlx::Error> {
30	sqlx::query_as!(
31	EndorsementRow,
32	"SELECT post_id, endorser_id FROM post_endorsements WHERE post_id = ANY($1)",
33	post_ids,
34	)
35	.fetch_all(pool)
36	.await
37	}
38
39	/// Per-post endorsement counts, aggregated in Postgres.
40	///
41	/// A `GROUP BY` returns at most one row per visible post regardless of how many
42	/// endorsements that post has, rather than streaming every endorsement row into
43	/// the app to `len()` it. Posts with zero endorsements are absent; the caller
44	/// defaults them to 0.
45	#[tracing::instrument(skip_all)]
46	pub async fn count_endorsements_for_posts(
47	pool: &PgPool,
48	post_ids: &[Uuid],
49	) -> Result<Vec<EndorsementCount>, sqlx::Error> {
50	sqlx::query_as!(
51	EndorsementCount,
52	r#"SELECT post_id, COUNT(*) AS "count!"
53	FROM post_endorsements
54	WHERE post_id = ANY($1)
55	GROUP BY post_id"#,
56	post_ids,
57	)
58	.fetch_all(pool)
59	.await
60	}
61
62	/// The subset of `post_ids` the given user has endorsed. Bounded by the page's
63	/// post count (not the endorsement total), so the thread view can mark the
64	/// viewer's own endorsements without loading every endorser id.
65	#[tracing::instrument(skip_all)]
66	pub async fn list_user_endorsed_posts(
67	pool: &PgPool,
68	post_ids: &[Uuid],
69	user_id: Uuid,
70	) -> Result<Vec<Uuid>, sqlx::Error> {
71	sqlx::query_scalar!(
72	"SELECT post_id FROM post_endorsements WHERE post_id = ANY($1) AND endorser_id = $2",
73	post_ids,
74	user_id,
75	)
76	.fetch_all(pool)
77	.await
78	}
79